People use electronic social networking services as tools for building and maintaining networks of personal, familial, academic, professional, and other interpersonal relationships. Collectively, a user's network of relationships is referred to as the user's social graph. For a mobile device client accessing these social networking services, the user's social graph can reside in a contacts list (e.g., a phone address book) stored on the mobile device. Communication within subgroups of contacts from such a contacts list may be difficult for a user. Moreover, additional functionality for one or more subgroups of the user's contacts may not be easily extensible.